Rapid shallow breathing (RSB) is a disorder associated with shortness of breath or difficult breathing (the subjective feeling of being out of breath) caused by heart or lung disorders, strenuous activity, high anxiety or stress. One form of RSB, termed dyspnea, derives from interactions among multiple physiological, psychological, social, and environmental factors, and may induce secondary physiological and behavioral responses. Dyspnea is different from tachypnea (rapid breathing) and hyperpnea (deep breathing). Tachypnea and hyperpnea can occur with hyperventilation, or over breathing beyond what is required to maintain arterial blood gases within normal limits. Fear or anxiety may create even more distress in dyspnic patients.
Dyspnea may be classified as chronic, acute, or terminal. Chronic dyspnea has a variable intensity and is associated with persistent shortness of breath. This is most often seen in patients with chronic obstructive pulmonary disease (COPD). Acute dyspnea causes episodes of shortness of breath with high intensity. It may be seen in patients who have suffered a myocardial infarction or pulmonary embolism. Terminal dyspnea occurs in patients with end-stage diseases, and these patients may be in a hospital, at home, or in a hospice. This type of dyspnea is a common complaint in patients with cancer. Dyspnea can be caused by a variety of conditions, including metabolic, allergic, psychiatric, and neuromuscular disorders, and by pain. However, cardiac and pulmonary disorders are the most common causes.
It is estimated that nearly one million hospital admissions for acute decompensated heart failure (HF) occur in the United States each year, which is almost double the number admitted 15 years ago. The re-hospitalization rates during the 6 months following discharge are as much at 50%. Nearly 2% of all hospital admissions in the United States are for decompensated HF patients, and heart failure is the most frequent cause of hospitalization in patients older than 65 years. The average duration of hospitalization is about 6 days. Despite aggressive therapies, hospital admissions for HF continue to increase, reflecting the prevalence of this malady.